'3     0jK 


Circular  No    t3.  Second  Series 


United  State 


)epartmen1  of  Am 

NTOMOLOOY. 

ni  s  wi>  M  I  vs. 


MOSQUITOES 

ni  inii  a  single  Bpeci 
,,f  ii,  n  mo9l  parte  of  the  countrj .  but  as  a 

italogueof  the  I  >iptera  records  twentj  one  spe<  ii  -  From 

North  Ann  ind   Mi     I     W     I  rich  Btates  thai  he  has  observed  al 

:,n  -p. .  i.     in  Trinidad.     Twenty  Bpecies  are   contained  in    the 

rollection  of  the  I  .  tf.  National  Museum. 

The  follow  im.:  statement  concerning  the  lit'-'  history  of  these  insects  ie 

I  upon  :i  series  of  observations  made  in   this   Division   upon   the 

development  of  two  summer  generations  of  Culex  pungens,  one  of  our 

coini:  ind  most  widespread  species.     The  writer  has  seen  speci- 

-  of  this  insect  from   NTew  Hampshire,   Massachusetts,    New   York. 

and,  District  of  Columbia,  Illinois,  Minnesota,  Kentucky,  Nebraska, 

orgia,  and  the  Island  of  Jamaica,  West  Indies.     No  doubt 

Ibo  abundant  in  New  J<  n 

■laying  takes  place  :it   night.     The  eggs  are  deposited  in  boat- 
Bhaped  masses  on  the  surface  of  the  water,  the  number  varying  from 
each  mass.     Thi  may  hatch  in  Bixteen  hours.     The 

larva;  live  beneath  the  surface  of  the  water,  coming  to  the  top  ai  fre- 
quent intervals  to  breathe.  The  larval  Btate  may  be  completed  inseven 
days;  the  pupil  state  may  last  only  twenty-four  hours.  An  entire  gen- 
eration in  summer  time,  then,  may  be  completed  in  ten  days.  This 
th  of  time,  however,  may  be  almost  indefinitely  enlarged  if  the 
weather  be  cool.  There  are.  therefore,  many  generations  in  the  course 
-on  and  the  insect  may  breed  successfully  in  a  more  or  less 
transient  Burface  pool  of  water. 

Mosqoitoi  -  hibernate  in  the  adult  condition  in  cellars  and  outhouses 
and  under  all  sorts  of  shelter.  The  degree  of  cold  makes  no  difference 
in  successful  hibernation  :  mosquitoes  are  abundant  in  the  arctic  regions. 

REMEDIES. 

remedies  against    mosquitoes   in   houses  the  best  is  a  thoro 
ning  of  windows  and  the  placing  of  nets  about  beds.     It  tin  vat 
are  troublesome  in  Bitting  ioms  during  the  evening,  the 

burning  of  pyrethrum  will  bo  stupefy  them  as  to  make  their  presence 
unobjectionable.     Pyrethrum  for  this  pu  ould  be  prepared  by 

moistening  the  powder  sufficiently  to  allow  of  it<  being  roughly  molded 
!>y  hand  into  little  cones  about  the  Bize  and  Bhape  of  a  large  chocolate 
drop.     These  cor  'hen  placed  in  a  pan  and  thoroughly  dried  in 

an  oven.  When  fired  at  the  apex,  Buch  a  cone  will  smoulder  slowly, 
and  send  up  a  thin  column  of  pungent  -moke,  not  hurtful  to  man.  but 
stupefying  to  mosquitoes.  In  actual  experience  two  01  three  Buch  cones 
burned  during  the  course  of  an  evening  have  given  much  relict  from 
mosquitoes  in  Bitting  room-.  It  does  not  kill  the  insects,  however,  and 
t  best  hut  a  palliative. 


2 

The  mosquitoes  found  on  the  ceilings  of  bedrooms  in  the  evening 
may  be  quickly  and  easily  killed  by  means  of  a  small  shallow  tin  cup 
(such  as  the  lid  of  a  blacking  box)  nailed  to  the  top  of  a  stick  and  wet 
inside  with  kerosene.  This  cup  is  placed  over  the  quiescent  mosquito, 
which  immediately  drops  or  flies  against  the  oily  surface  and  is  killed. 
But  altogether  the  most  satisfactory  means  of  lighting  mosquitoes  are 
those  which  are  directed  to  the  destruction  of  the  larva'  or  the  abolition 
of  breeding  places.  These  measures  are  not  everywhere  feasible,  but  in 
many  places  there  is  absolutely  no  necessity  for  the  endurance  of  the 
mosquito  plague.  The  principal  remedies  of  this  class  are  three  :  The 
draining  of  ponds  and  marshes,  the  introduction  of  fish  into  fishless 
pools,  and  the  use  of  kerosene  on  the  surface  of  the  water. 

The  draining  of  breeding  pools  needs  no  discussion.  Obviously  the 
drying  up  of  such  places  will  prevent  mosquitoes  from  bleeding  therein, 
and  the  conditions  of  a  successful  application  of  this  measure  will,  it  is 
equally  obvious,  vary  with  each  case. 

The  introduction  of  fish  into  fishless  ponds  is  feasible  and  advisable 
in  many  cases  where  the  use  of  kerosene  on  the  surface  of  the  water 
would  be  thought  undesirable.  In  tanks  supplying  drinking  water,  for 
example,  fish  would  destroy  the  mosquito  larva'  as  fast  as  hatched.  A 
case  is  recorded  in  Insect  Life  (Vol.  IV,  p.  223)  where  carp  were 
employed  in  this  way  with  perfect  success  by  an  English  gentleman 
living  in  the  Riviera.  At  San  Diego,  Tex.,  the  people  use  for  this  pur- 
pose a  little  fish,  called  there  a  perch,  the  species  of  which  the  writer 
has  not  been  able  to  ascertain.  Probably  the  common  voracious  little 
stickle-back  would  answer  admirably  as  a  mosquito  destroyer. 

Probably  the  best,  and  certainly  the  easiest,  of  wholesale  remedies 
against  mosquitoes  is  the  application  of  kerosene  to  the  surface  of 
breeding  pools.  The  suggestion  that  kerosene  could  be  used  as  a  remedy 
for  mosquitoes  is  not  new  and  has  been  made  more  than  once.  Exact 
experiments  out  of  doors  and  on  a  large  seale  were  made  in  1892  by  the 
writer.  These  and  subsequent  experiments  show  that  approximately  1 
ounce  of  kerosene  to  each  15  square  feet  of  water  surface  on  small  pools 
will  effectually  destroy  all  the  larva*  and  pupae  in  that  pool,  with  the 
additional  advantage  that  the  adult  females, not  deterred  from  attempt- 
ing to  oviposit,  are  killed  when  they  alight  on  the  kerosene-covered  water. 
Ordinarily  the  application  need  not  be  renewed  for  a  month,  though 
varying  circumstances  may  require  more  frequent  applications  in  certain 
cases. 

Since  1892  several  demonstrations,  on  large  and  small  scales,  have 
been  made  of  the  practicability  of  this  method.  Under  the  writer's 
supervision  two  localities  were  rid  of  mosquitoes  by  the  use  of  kerosene 
alone.  It  will,  however,  probably  not  prove  feasible  to  treat  in  this 
way  the  large  sea  marshes  along  the  coast  where  mosquitoes  breed  in 
hordes,  although  even  here  the  remedy  may  prove  to  he  practicable 
under  certain  conditions  and  in  certain  situations.  In  inland  places. 
however,  where  the  mosquito  supply  is  derived  from  comparatively  cir- 
cumscribed pools,  the  kerosene  remedy  will  prove  most  useful.  In 
some  California  towns,  we  are  informed,  the  pit  or  vault  behind  water- 
closets  is  subject  to  flushing  with  water  during  the  irrigation  of  the 
land  near  by.  A  period  of  several  weeks  elapses  before  more  water  is 
turned  in,  and  in  the  meantime  the  water  in  the  pit  grows  stagnant  and 
becomes  the  breeding  place  of  thousands  of  mosquitoes.  Where,  as  in 
certain  towns  and  cities,  house  drainage  runs  into  such  a  pit  and  an 


outdoor  privy  with  a  seldom  closed  door  is  built  ovei  it,  mosquitoes  will 
breed  .ill  summer  in  the  fluid  contents  of  the  vault  and  of  course  will 
infest  all  tlir  adjacent  hoi; 

In  such  teacupful  of  kerosene  poured  into  each  vault  at  ii 

vals  of  a  month  or  less  would   greatlj    d  the  annoyance  from 

mosquitoes,  it  it  did  not  altogether  prevt  nt  it.     This  i  where  the 

cooperation  of  neighbors  is  mo  eholder  in  a  given 

neighborhood  Bhould  see  that  his  vault  is  treated  with  ki  ularly 

ami  often.     'I'll'-  cost  i-  bo  trifling  that  it  me. I  imt  be  considered. 

Where,  as  is  thi  I  many  country  homes,  rain  v  ollci  ted 

in  barrels  or  purpose  or  another,  mosquitoes  may 

ami  do  breed  in  numbers  in  such  vessels.     If  the  v  b<  drawn 

in  >i  n  tlir  I  xit  ton  i  (if  the  cask,  it  will  do  no  harm  i"  pour  in  a  little  kero- 
sene, since  tin1  nil  will  not  be  drawn  out  with  the  water.  At  all  events, 
rach  receptacles  should  b<  1  at  night  to  prevent  egg-layi 

The  question,  What  is  the  besl  way  to  cover  with  kerosene  the  sur- 
of  a  pool  of  some  Bize?  is  apparently  Mir  operation 

is  obviously  simple,  but  Buch  a  question  has  been  asked  of  the  Divit 
Simply  pouring  tlir  oil  on  from  any  point  of  the  shore  will  answer  tol- 
erably well,  since  it  will  spread  of  itself,  but  if  for  any  reason  it  is  desired 
to  coal  tlic  pool  rapidly  with  kerosene,  it  may  be  advisable  to  spray  tin- 
oil  through  a  Bpraying  nozzle,  either  from  the  bank  or  from  a  boat.  The 
method  of  application  will  vary  with  each  case,  but  in  the  class  of  pools 
which  can  he  most  advantageously  treated,  namely,  those  "t  -iii.. II  size, 
the  oil  can  he  well  spread  by  throwing  it  on  to  windward  with  a  wide 

sweep  of  the  arm. 

II.-FLEAS. 

Judging  from  the  specimen-  "i  fleas  si  ut  to  the  Division  of  late  years, 
with  complaints  of  bouses  infested  by  them,  the  human  Ilea  {Pulex 
irritans)    \>  not   the  species  most    likely  to  occur  in  Urr-at  numbers  in 

dwelling  house.-,  hut  rather  the  common  cos politan  flea  of  th< 

and  cat  {Pulex  serraticeps).  A  house  may  become  infested  with  this 
species,  even  though  no  domestic  animals  he  kept,  for  a  visitor  at  a 
house  where  such  pets  are  maintained  may  he  the  means  of  carrying 
home  with  him  one  or  two  female  fleas  which  will  <tock  hi-  own  prem- 
Of  course  where  a  pet  dog  or  cat  i-  kept  the  source  of  the  infes- 
tation is  manifi  - 

The  wor.-t  cases  of  infestation  reported  to  thi-  Division  were  where 
houses  had  heen  temporarily  unoccupied  during  the  summer.  Such 
houses  often  hecome  more  or  less  damp,  and  a-  a  rule  the  customary 
Bweeping  of  the  floors  is  interrupted,  thus  furnishing  the  very  conditions 
under  which,  as  we  shall  Bee,  ilea-  most  readily  pi 

The  eggs  of  I'nh  i-  serraticeps  are  deposited  among  the  I 
and  do'^s.  hut  as  they  are  not  attached  to  the  hair-,  numbers  drop  off 
whenever  the    infested  animal  move-  or  lie-  down.      I  rimenters 

who  desire  to  follow  out   for  themselves  the  life  history  of  th- 
an easy  way  to  collect  tin-  eggs  i-  therefore  to  lay  a  strip  of  cloth  01 
pet  for  the  animal  to  Bleep  upon,  ami  afterward-  to  brush  the  cloth  into 
a  receptacle,  in  which  the   eggs  will  he  found  in  numbers  if  the  animal 
is  infested.      In  this  lies  a   hint    for  the   housekeeper  who  wmild  k- 
pet  dog  or  cat  and  yet  avoid  an  outbreak  of  fleas  in  the  house.      Provide 
a  nii.'  for  the  cat  or  the  dog  to    -lee])  on    and    L'ive    this    rug    a    frequent 
shaking  and  brushing,  afterwards  Bweeping  up  and  burning  the  dust 
thus  removed.      A?  all  the  flea  eggs  on  an  infested  animal  will  not.  how- 


UNIVERSITY  OF  FLORIDA 


4 

3  1262  09216  4846 
ever,  drop  off  in  this  way,  and  those  which  remain  on  it  will  probably 
1 1. -v. •lop  successfully,  it  will  be  found  wise  to  occasionally  rub  into  the 
hair  of  the  dog  or  cat  a  quantity  of  pyrethrum  powder.  '  If  thoroughly 
applied  it  will  cause  the  fleas  to  fall  off  in  a  half  stupefied  condition, 
when  they,  too,  may  be  swept  up  and  burned. 

In  the  observations  made  at  this  Department  upon  this  species  of  flea 
during  the  summer  of  1895,  some  difficulty  was  found  in  preserving  just 
the  right  degree  of  moisture  to  enable  the  insect  successfully  to  trans- 
form. An  excess  of  moisture  was  found  prejudicial  to  the  development 
of  the  species,  as  was  too  great  dryness.  The  observations  showed, 
however,  that  at  Washington  in  summer  an  entire  generation  may 
develop  in  a  little  more  than  a  fortnight.  Hence  a  housekeeper  shut- 
ting up  her  house  in  .June,  for  example,  with  a  colony  of  fleas  too  small 
to  be  noticed  inside  it,  need  not  he  surprised  to  find  the  establishment 
overrun  when  she  opens  it  up  again  in  September  or  October. 

REMEDIES. 

The  larva-  of  the  dog  and  cat  Ilea  will  not  develop  successfully  in 
situations  where  they  are  likely  to  he  disturbed:  The  use  of  carpets 
and  straw  mattings,  in  our  opinion,  favors  their  development,  sine,  ' 
young  larvae  can  penetrate  the  interstices  of  either  sort  of  Moor-covering 
and  find  an  abiding  place  in  some  crack  where  they  are  not  likely  to  be 
disturbed.  It  is  comparatively  easy  to  destroy  the  insect  in  its  early 
stages  (when  it  is  noticed),  as  is  shown  by  the  difficulty  of  rearing  it, 
but  the  adult  fleas  are  so  active  and  so  hardy  that  they  successfully 
resist  any  but  the  most  strenuous  measures.  Even  the  persistenl  use 
of  California  buhach  and  other  pyrethrum  powders  was  ineffectual  in 
one  case  of  extreme  infestation,  as  was  also,  and  more  remarkably,  a  free 
sprinkling  of  floor  mattings  with  benzine.  In  this  instance  it  v 
finally  necessary  to  take  up  the  floor  coverings  and  wash  the  floors  down 
with  hot  soapsuds  in  order  to  secure  relief  from  the  flea  plague.  In 
another  case,  however,  a  single  liberal  application  of  buhach  was  per- 
fectly successful,  while  in  a  third  a  single  thorough  application  of  ben- 
zine completely  rid  an  infested  house  of  fleas. 

To  sum  up:  Every  house  where  a  pet  dog  or  cat  is  kept  mav  become 
seriously  infested  with  fleas  if  the  proper  conditions  of  moisture  and 
freedom  from  disturbance  exist.  Infestation,  however,  is  not  likely  to 
occur  if  the  (hare)  floors  can  be  frequently  and  thoroughly  swept. 
When  an  outbreak  of  fleas  comes,  however,  the  easiest  remedy  to  apply 
is  a  free  sprinkling  of  pyrethrum  powder  in  the  infested  rooms.  This 
failing,  benzine  may  be  tried,  a  thorough  sprayii  pets  and  floors 

being  undertaken,  with  the  exercise  of  due  precaution  in  seeing  that  no 
lights  or  (ires  are  in  the  house  at  the  time  of  the  application,  or  for  some 
hours  afterwards.  Finally,  if  the  plague  is  not  thus  abated,  all  floor 
coverings  must  be  removed  and  the  floors  washed  with  hot  soapsuds. 
This  is  a  useful  precaution  to  take  in  any  house  which  it  is  proposed  to 
dose  for  the  summer,  since  even  a  thorough  sweeping  may  leave  behind 
some  few  flea  eggs  from  which  an  all-pervading  swarm  may  develop 
before  the  house  is  reopened. 

L.  ().  Howard, 
Approved :  Entomologist. 

t'n  \^.  W.  Dabney,  Jr., 

A ssistant  Secretary. 

Washington,  D.  C.  February  l.  1896. 


